1. Technical Field
The present invention relates to a stacked-layered thin film solar cell and a manufacturing method thereof. More particularly, the present invention relates to an insulation structure in a stacked-layered thin film solar cell.
2. Description of Related Art
Please refer to FIG. 1A for a stacked-layered thin film solar cell in the prior art. As shown in the drawing, a stacked-layered thin film solar cell 1 comprises a substrate 14, a first electrode layer 11, a semiconductor layer 13 and a second electrode layer 12 stacked together. In a manufacturing process of the stacked-layered thin film solar cell 1, the substrate 14 is deposited with the first electrode layer 11, which is then treated with laser scribing to form a plurality of unit cells 112 divided by a plurality of grooves 111. Following that, the semiconductor layer 13 is deposited on the first electrode layer 11 and treated with laser scribing, so that each groove cut into the semiconductor layer 13 is approximately 100 μm from an adjacent groove 111 cut into the first electrode layer 11. Next, the second electrode layer 12 is deposited on the semiconductor layer 13, and the second electrode layer 12 and the semiconductor layer 13 are treated with laser scribing to form a plurality of grooves 121 cut into the second electrode layer 12 and the semiconductor layer 13, each of which grooves 121 is approximately 100 μm from an adjacent groove 131 cut into the semiconductor layer 13. Thus, by depositing the aforesaid layers and performing laser scribing thereon, the stacked-layered thin film solar cell 1 is formed with the plurality of unit cells 112 connected in series.
The photoelectric conversion efficiency of a stacked-layered thin film solar cell has its limit owing to such factors as recombination of electrons and electron holes and loss of light. Therefore, during the manufacturing process, an interlayer is often added between a material having a high energy level and a material having a low energy level, so that when light penetrates the stacked-layered thin film solar cell, a portion of the light that has relatively short wavelengths and can be absorbed by the material having the high energy level will be reflected, thereby increasing a light path. Meanwhile, a portion of the light that has relatively long wavelengths and cannot be absorbed by the material having the high energy level will reach the material having the lower energy level, thereby increasing light transmission. For instance, U.S. Pat. No. 5,021,100 discloses a stacked-layered thin film solar cell integrated with a dielectric selective reflection film. However, the interlayer, which serves to connect materials having different energy gaps, has a certain degree of electric conductivity and may cause current leakage or short circuit during an edge insulation treatment in the manufacturing process, Hence, referring to FIG. 1B, U.S. Pat. No. 6,632,993 adds circuit-breaking grooves 161 cut into an interlayer 16 for interrupting current flow in the interlayer 16 and thereby preventing current leakage. Referring now to FIG. 1C, U.S. Pat. No. 6,870,088 adopts a similar approach except that grooves 18 are cut into a photoelectric conversion layer and provided between two circuit-breaking grooves 171 to prevent the aforementioned problem. Although insulation can be achieved in the U.S. Pat. Nos. 6,632,993 and 6,870,088 by forming circuit-breaking grooves cut into specific layers, the additional processing steps and costs are disadvantageous to mass-production manufacturers. Therefore, it is a pressing issue to solve the short-circuit problem of the interlayer at a low production cost.